1. Field of the Invention
This invention relates to the dispensing of liquids in the form of aerosolized liquid droplets and more particularly it concerns novel methods and apparatus for the aerosolized dispensing of liquids with a minimum of spillage.
2. Description of the Related Art
U.S. Pat. Nos. 5,164,740 and 5,938,117 show and describe devices for causing a liquid to be dispensed into the atmosphere in the form of minute liquid droplets. These devices comprise a thin orifice plate formed with minute orifices extending therethrough. The plate is vibrated at a high frequency while the liquid to be dispensed is maintained in contact with the underside of the plate. The vibratory movement of the plate causes the liquid to be pumped through the orifices in the plate and ejected into the atmosphere from its upper surface.
U.S. Pat. No. 5,518,179 shows a similar liquid dispenser wherein a capillary feed, such as a wick, is used to draw the liquid to be dispensed up from a reservoir to the lower surface of the vibrating plate.
Similar vibratory type liquid dispensers are shown and described in U.S. Pat. Nos. 4,790,479, 4,793,339, 5,518,179, 5,529,055 and 5,915,377.
It is also known to dispense vapors such as fragrances, air fresheners and other aromatics which are contained in a gell or in a solids suspension. Such vapor dispensing arrangements are shown and described in U.S. Pat. Nos. 5,419,879, 5,575,992, 5,637,401, 5,647,052, 5,788,155 and 5,885,701.
A problem is encountered when using a vibrating plate type dispenser to aerosolize certain low viscosity liquids such as liquid fragrances and liquid air fresheners. Such liquids easily pass through very minute orifices; and there is a tendency for the liquid to seep and leak out through mating surfaces in the dispenser assembly. There is also a danger of spillage when a refill reservoir is mounted in the dispenser assembly.
Although it is known to dispense some fragrances and aromatics from a gell or colloidal solid suspension, such fragrances and aromatics are evaporated from the solid suspension and are dispersed therefrom in the form of a vapor. It is not possible to dispense such fragrances and aromatics in the form of liquid droplets because the suspension is too thick or viscous to pass through the minute orifices of a liquid atomizing device such as a vibrating orifice plate.
This invention is based on the discovery that by providing a capillary element between a solids suspension and a vibrating orifice plate, the liquid component of the suspension becomes separated from the other material in the suspension whereby the liquid can be pumped through the plate orifices and dispersed into the atmosphere in the form of aerosolized droplets.
According to one aspect of the invention, there is provided a novel apparatus for generating aerosolized liquid droplets. This novel apparatus comprises an orifice plate formed with minute orifices extending therethrough in a given direction and a vibrator arranged to vibrate the orifice plate at high frequency in such given direction. A reservoir is located below the orifice plate and contains therein, a liquid to be aerosolized. The liquid is held in a solids suspension within the reservoir. A capillary element contacts the liquid within the reservoir and extends up out of the reservoir to the orifice plate. With this arrangement, the liquid is separated from the solids suspension and is pumped through the orifices in the plate and ejected into the atmosphere in the form of aerosolized liquid particles. Because the liquid is held in a solids suspension in the reservoir it has a high bulk viscosity and is not prone to leakage or spillage.
According to another aspect of the invention, there is provided a novel method of dispensing a liquid into the atmosphere in the form of minute aerosolized particles. This novel method comprises the steps of forming a solids suspension containing a liquid to be dispensed; and causing the liquid to be drawn up from the solids suspension through a capillary element to the lower surface of a vibrating orifice plate. The liquid becomes separated from the solids suspension and is pumped through minute orifices in the orifice plate and ejected into the atmosphere in the form of aerosolized particles.